Long-term effects of four extraction media on the fluoride release from four polyacid-modified composite resins (compomers) and one resin-modified glass-ionomer cement

It was the aim of the present experiments to evaluate the fluoride leaching of four compomers and one resin-modified glass-ionomer cement (gic) into aqueous media over a 1-year period. Various extraction/equilibrium solutions were applied to simulate important intraoral parameters. Specimens of Dyract (TM), Compoglass (TM), F, F2000 (TM), one experimental compomer, and the resin-modified gic Fuji II LC (TM) were stored for 366 days in distilled water (I), acidic medium (pH 4.2) (II), neutral medium (pH 7.0) (III), or solution III supplemented with 1.6 u/mL porcine liver esterase (IV). Equilibrium media were changed and fluoride concentration was measured every 48 h (first 30 d), thereafter each week (twice), then every 14 d (three times), and finally every 28 d up to a total period of 1 year. Data were statistically analyzed for significant differences by means of Scheffe' tests (p < 0.05). The gic and the compomers leached significantly more fluoride into the acidic solution in the initial phase compared to the other media (p < 0.05). Cumulative fluoride release from all materials (except experimental compomer) was elevated because of esterase activity (p < 0.05). Measurable but low quantities of fluoride were segregated into all media during the 1-year period. But no significantly different long-term fluoride release into the various media from the investigated materials was found. The data indicate that plaque-associated organic acids or salivary hydrolases may increase initial fluoride release from resin-modified gics or compomers In the oral cavity. Because long-term fluoride release from all materials decreased to low concentrations within a 30-day period, their caries preventive effect remains questionable. (C) 2001 John Wiley & Sons, Inc.